Bardskull

Product Information

a b Rashid, Dana J; Chapman, Susan C; Larsson, Hans CE; Organ, Chris L; Bebin, Anne-Gaelle; Merzdorf, Christa S; Bradley, Roger; Horner, John R (2014). "From dinosaurs to birds: a tail of evolution". EvoDevo. 5 (1): 25. doi: 10.1186/2041-9139-5-25. ISSN 2041-9139. PMC 4304130. PMID 25621146. a b Ornithology, The Cornell Lab of. "All About Bird Anatomy from Bird Academy". academy.allaboutbirds.org . Retrieved 2018-05-11. Despite the wide variety of colors, shapes, and sizes, all bird beaks consist of the upper jaw (maxilla), lower jaw (mandible), and the keratinized outer layer (Rhamphotheca) that covers them. Let’s take a closer look at some of the most important features of a bird’s beak. Mandible and Maxilla

Bezuidenhout, A.J.; Groenewald, H.B.; Soley, J.T. (1999). "An anatomical study of the respiratory air sacs in ostriches" (PDF). Onderstepoort Journal of Veterinary Research. The Onderstepoort Veterinary Institute. 66 (4): 317–325. PMID 10689704 . Retrieved 2014-01-21. The upper leg consists of the femur. At the knee joint, the femur connects to the tibiotarsus (shin) and fibula (side of lower leg). The tarsometatarsus forms the upper part of the foot, digits make up the toes. The leg bones of birds are the heaviest, contributing to a low center of gravity, which aids in flight. A bird's skeleton accounts for only about 5% of its total body weight. Birds have a four-chambered heart, [62] in common with mammals, and some reptiles (mainly the crocodilia). This adaptation allows for an efficient nutrient and oxygen transport throughout the body, providing birds with energy to fly and maintain high levels of activity. A ruby-throated hummingbird's heart beats up to 1200 times per minute (about 20 beats per second). [63] Digestive system [ edit ] Pigeon crop containing ingested food particles is highlighted in yellow. The crop is an out-pouching of the esophagus and the wall of the esophagus is shown in blue. Simplified depiction of avian digestive system. Crop [ edit ] Alimentary canal of the bird exposedThe shoulder consists of the scapula (shoulder blade), coracoid, and humerus (upper arm). The humerus joins the radius and ulna (forearm) to form the elbow. The carpus and metacarpus form the "wrist" and "hand" of the bird, and the digits are fused together. The bones in the wing are extremely light so that the bird can fly more easily. Birds are incredibly successful organisms that have diversified into thousands of ecologically distinct species all over the world. We think their paedomorphism contributed to this success. Although birds have lungs, theirs are fairly rigid structures that do not expand and contract as they do in mammals, reptiles and many amphibians. Instead, the structures that act as the bellows that ventilate the lungs are the air sacs, which are distributed throughout much of the birds' bodies. [52] The airsacs move air unidirectionally through the parabronchi of the rigid lungs. [53] [54]

Some birds, such as pigeons, geese, and red-crowned cranes, remain with their mates for life and may produce offspring on a regular basis. The origins of living bird diversity are shrouded in mystery — other than knowing that modern birds arose at some point towards the end of the age of dinosaurs, we have very little fossil evidence of them until after the asteroid hit,” said co-author Albert Chen, a PhD student based at Cambridge. “This fossil provides our earliest direct glimpse of what modern birds were like during the initial stages of their evolutionary history.” The notable exception is the family of pigeons and doves, the Columbidae; in fact, according to Konrad Lorenz in 1939: This section needs additional citations for verification. Please help improve this article by adding citations to reliable sourcesin this section. Unsourced material may be challenged and removed. ( September 2018) ( Learn how and when to remove this template message)Dr Abzhanov said: “One other useful outcome of this survey of skulls from across reptile evolution was a better ability to recognise the (often disputed) evolutionary fates of individual cranial bones, especially during the dramatic reptile to bird transition.” Proctor, N. S. & Lynch, P. J. (1998) Manual of Ornithology: Avian Structure & Function. Yale University Press. ISBN 0300076193

It may be easier to say what Bardskull is not. It’s not a memoir. It’s not poetry. It’s not a compendium of myths and ancient wisdom. It is, rather, all of these things, plus some faux-naive drawings, loosely structured around an autofictional account of several journeys that oral storyteller Martin Shaw seems to have undertaken on Dartmoor over the course of 101 days, a kind of wilderness journey. Or in Shaw-speak: “I walked out one summer morning and barely ceased till St George’s Day of the next year … These are words from the rough, from the stomp. Things hurtled through me, old things. I am not the same.” Lynch, Wayne; Lynch, photographs by Wayne (2007). Owls of the United States and Canada: a complete guide to their biology and behavior. Baltimore: Johns Hopkins University Press. p.151. ISBN 978-0-8018-8687-4. So, as birds evolved to live in different environments and feed on various food sources, their bills evolved into shapes and sizes best suited to capture/collect and process that food.

About

Smith, Nathan D. (2011). "Body mass and foraging ecology predict evolutionary patterns of skeletal pneumaticity in the diverse "waterbird" clade". Evolution. 66 (4): 1059–1078. doi: 10.1111/j.1558-5646.2011.01494.x. PMID 22486689. S2CID 42793145. a b Arnqvist, G.; I. Danielsson (1999). "Copulatory Behavior, Genital Morphology, and Male Fertilization Success in Water Striders". Evolution. 53 (1): 147–156. doi: 10.2307/2640927. JSTOR 2640927. PMID 28565197. Our study adds further evidence that adult modern birds share much in common with juvenile (non-avian) dinosaurs, an observation which led to the revelation about a specific adjustment to the embryonic development in their ancestor.” Developing and evolving